Production of ferrocobalt



- Aug. 18, 1936. BQSIQUI 2,051,433

PRODUCTION OF FERROGOBALT Filed June 29, 1933 .FTLBosgw.

Patented Aug. 1a, 1936 UNITED STATES 2,051.43: raonoc'rrosor rsnnoconsur Francis Lawrence Bosqui,

NKana, Northern Rhodesia, minor to Bhokana Corporation Limited, N'Kana, Northern Rhodesia Application June 29, 1933, Serial No. 678,299

lclaim.

In the metallurgical treatment of copper ores containing notable quantities of cobalt the latter metal may, by reduction of the copper slag, be obtained in the form of an alloy or mixture comprising cobalt, iron and copper. The object of the invention is to provide an electrolytic process whereby'ferro-cobalt with a high degree of purity as regards-copper "may be obtained directly and cheaply from said alloy or mixture or similar material.

According to the invention, an alloy or mixture comprising iron, cobalt and copper is provided in which the copper does not exceed about 15% by weight. Said material is anodically corroded in an electrolytic cell, the electrolyte of which is substantially neutral, but is nevertheless on the acid side of neutrality. The free acid should be definitely below three grams per litre reckoned as sulphuric acid, otherwise copper would be deposited with the iron and cobalt; and in practice it is found desirable to maintain an amount of free acid ranging from one to two grams per litre, in order to keep the acidity of the electrolyte under control. During the operation of the electrolytic cell the copper content of the electrolyte is maintained at not more than about 0.05 gram per litre. Under these conditions cobaltand iron together are deposited as metal at the cathode whilst the copper content of the anode is for the most part left as sludge in the electrolytic cell.

The invention will be further described with reference to the accompanyin diagrammatic drawing in which:

Figure I illustrates the production cobalt in a single stage;

Figure 11 illustrates its production in several -of ferrostages.

Referring to Figure I, I indicates an open electrolytic cell, that is a cell in which the anode andkathode are not separated by a diaphragm. The anode 3 is, a casting of the raw material consisting of copper, iron and cobalt. The kathode 4 is a plate of material suitable for ferro-cobalt to plate onto such as rolled cobalt, iron, copper or stainless steel. I is a source of direct current such as to produce a current density of about 10 amperes per square foot of kathode area. The electrolyte 8 contains free acid, preferably sulphuric acid, to the extent of from one to two grams per litre.

Under these conditions the anode 3 is corroded; and, provided it does not contain an undue proportion of copper for instance not more than about fifteen per cent., there is deposited on the kathode a plating of commercially pure ferro-cobalt, that is ferro-cobait containing not more than about 0.5 per. cent. of copper.

The bulk of the copper appears as spon y cop- ,5- per and copper oxide. Some of this fails directly to the bottom of the cell. Some tends to collect on the anode surface and is brushed therefrom from time to time in order to prevent the anode surface from attaining too high a 10 copper percentage, which would result in copper going in undue quantity into thesolution.

A small amount of copper goes into solution and, unless controlled, it wouldbuild upin the electrolyte and deposit as metal on the kathode l5 and thereby contaminate the .ferro-cobalt. This, however, does not occur to any detrimental extent until the copper concentration of the electrolyte exceeds 0.05 gram per litre. The electrolyte may accordingly. be treated to prevent 20 the concentration from rising above that figure. This may be done by withdrawing a portion of the electrolyte, preferably continuously, treating such portion for the removal of its copper content and returning it to the cell. 5 Such treatment conveniently consists in cementing the copper on to scrap iron or comminuted cobalt.

For this purpose the cell is provided'with an outlet 1 from which the electrolyte can be continuously withdrawn at a rate controlled by the valve 0. It is then percolated through a mass 9 of materialonto' which it will cement such as scrap iron or comminuted cobalt or the ferrocobalt product of the process. The latter is convenient owing to the physical form in which it often occurs, viz. as thin twisted and brittle scales, which are readily detached from the kathode and offers large surface for the deposition of the copper.

The purifled electrolyte is received at I! and returned to the cell as indicated by H.

The cement copper recovered at I as well as the copper sludge taken from the cell are, in favourable physical and chemical condition for the recovery of the copper contents in pure form, as by smelting as indicated at l2.

The ferro-cobalt deposited at the its. bodes is detached therefrom, melted under slightly reducing conditions and cast into shapes suitable for marketing.

when the copper content of the raw metal is high, say above fifteen per cent., the copper content of the deposited ferro-cobalt is correspondingly high. In order to obtain substantially pure term-cobalt from raw metal high in copper, the operation is conducted in two or more stages as illustrated in Figure Ii. The impure term-cobalt obtained in the call I is melted and cast into anodes 3a which are corroded in a cell In under the same conditions as in cell 2. strict adherence to :the acid limitations mentioned above is not so essential in the preliminary purification stage or stages since, although an increase of acidity'would permit the depositional copper to an extent which would not occur if the acid 1 m:

its were adhered to, there is still a substantial reduction oi the copper content relatively 'to the mm m an electrolytic cell, the electrolyte ot which contains acid in amount less than three 7 grams per litre reckoned as sulphuric acid, thereby producing in the cell a cathodedeposit of cobalt and iron containing less copper than the anode, repeating the step. it necessary, by using the cathode material of the earlier step as anode material in the later step until the material contains from trace to about 15% by weight of copper, thenanodlcally corroding such material in 10 an electrolytic cell the electrolyte 01' which contains free acid less than three grams per litre reckoned as sulphuric acid.'-and the copper content oi which does not exceed about 0.05 gram per litre, thereby anodically depositing iron and 'cobalt'tog'ether substantially free from copper and causing the greater part of the remaining copper to deposit in the cell as sludge. v FRANCIS LAWRENCEBOSQUI. 

